Due to ever increasing antibiotic resistance, new anti-bacterials of novel structure have become very important to the treatment of bacterial infections (J. Med. Chem 39, 3853, 1996).
Kinoshita (J. Antibiotics 48, 437, 1995) has revealed various pyralomicins. ##STR2##
These compounds were isolated from Microtetraspora spiralis and display good activity vs Micrococcus luteus, but relatively poor activity versus Staphylococcus aureus. The compounds all contain the sugar moiety and are thus higher molecular weight.
Soliveri reveals pyrazaloisoquinolenones from Streptoverticillium griseocarnum (J. Antibiotics 49, 700, 1996). ##STR3##
These compounds show poor activity versus Staphylococci and contain a ring system substantially different than that shown in Formula I.
Saturated fused ring systems have been reported (Tet. Lett 30, 7321, 1989; and 31, 6765, 1990) where the pyrrolidine and piperidine rings are fully saturated rather than aromatic. No biological activities were reported. ##STR4##
A method of preparation has been disclosed where a S replaces the oxygen of the benzoxazine ring system (J. Org. Chem. 57, 3676, 1992). The phenyl ring is not substituted and no biological activity is disclosed. ##STR5##
Sckrob et al. disclose ring systems where nitrogen has replaced the benzoxazine ring oxygen (J. Gen. Chem. USSR 38, 1970, 1968); no biological activities were revealed. ##STR6##